jordan form question

2)A)
find the definative polinomial and the minimal polinomial of
find the primary decomposition of in this case,and write the diagonal block matrices
similar to A
?
B)
find the jordan form of A defined in part A
and find the transformation matrices to the basis for which it represented in jordan form.
how i tried:
regarding A:
how i tried:
|tI-A|= = = =
=
there are some roots possible by theory t=1,-1,+28,-28
t=1: 1-8+24-28
t=-1: -1-8-24-28
from the calculator the other dont work too
??